A man pushes a shopping cart across a level floor. What force resists the effort force? A) gravity B) friction C) the normal for
1 answer:
Answer:
B) Friction
Explanation:
Friction is a force that acts when an object is sliding along a surface. Microscopically, this force is due to the fact that the two surfaces are not perfectly smooth, but they have "imperfections" that cause a force that opposes the motion of the object.
For an object sliding on a flat surface, the force of friction has magnitude:
where
is the coefficient of kinetic friction
m is the mass of the object
g is the acceleration of gravity
The direction of the force of friction is always opposite to the direction of motion of the object.
In reality, friction also acts if the object is at rest and it is pushed by a force; in this case, we talk about static friction, and its magnitude is
where is called coefficient of static friction, and it is generally larger than the coefficient of kinetic friction.
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Answer:
velocity = 62.89 m/s in 58 degree measured from the x-axis
Explanation:
Relevant information:
Before the collision, asteroid A of mass 1,000 kg moved at 100 m/s, and asteroid B of mass 2,000 kg moved at 80 m/s.
Two asteroids moving with velocities collide at right angles and stick together. Asteroid A initially moving to right direction and asteroid B initially move in the upward direction.
Before collision Momentum of A = 1000 x 100 = kg - m/s in the right direction.
Before collision Momentum of B = 2000 x 80 = 1.6 x kg - m/s in upward direction.
Mass of System of after collision = 1000 + 2000 = 3000 kg
Now applying the Momentum Conservation, we get
Initial momentum in right direction = final momentum in right direction =
And, Initial momentum in upward direction = Final momentum in upward direction = 1.6 x
So, =
m/s
and m/s
Therefore, velocity is =
=
= 62.89 m/s
And direction is
tan θ = = 1.6
therefore,
= from x-axis